Greylisting is an anti-spam technique that temporarily defers mail from sender combinations the server does not yet recognize. A correctly operating sending mail server normally retries the message, after which it can be accepted.
Enable or disable greylisting
If the feature is available, open cPanel → Email → Configure Greylisting and toggle greylisting for the desired domain.
What to expect
First-time mail from an unfamiliar sender can be delayed because the sending server must retry. The actual retry/defer timing is server-configurable, so do not assume a fixed delay.
Use Track Delivery when you need to see whether a message was deferred, delivered, filtered, or rejected.
